The aquarium guys tell me to go directly to a salt water tank. 'Course I'm sure they're just tryin' to make the sale.
Salt water is a lot prettier and prolly doesn't cost that much more than fresh water.
Sam's got a nice salt water tank at his house, so I'll defer to his opinion and knowledge of the difference.
I've had both fresh and salt and have to say that fresh is magnitudes easier. Not sure I'd go to salt again if I was just setting up. 'Course, if you can spend lots of time with it, salt would be OK.
One thing I found out was that the water temp in salt needs to be kept cooler than you'd think - somewhere in the mid 70's, I think. Fairy basslets (known to aquarium dealer as royal grammas) are the hardiest as well as being the prettiest fish for me. Purple and yellow. Atlantic natives as well.
It's a no brainer that a salt tank is far the most spectacular and pretty. But I did learn a good fresh water trick: if you can take the time to vacuum your fresh water tank once a week, the water will be so clear, and the fish so bright, that some folks will accuse you of having a salt water tank. It happened to me more than once.
Fish tanks are wonderful, tell you the truth.